In Cambodia, malaria is the 3rd leading cause for outpatient clinic visits and the most common cause of deaths in hospitalized patients. Malaria control efforts were reorganized during the1990s under the National Centre for Parasitiology, Entomology and Malaria Control (CNM), but in the aftermath of the Khmer Rouge regime, few experts remain. Increasing drug resistance confounds malaria control efforts, which focus primarily on Plasmodium falciparum. Very little is known about the epidemiology of P. vivax and the efficacy of current treatment strategies. The long term objective of this proposal is therefore to build capacity in Cambodia by training physicians, scientists, university students and laboratory technologists in the skills necessary for effective vivax malaria control. The specific aims of this proposal over the next five years are to 1) Train 2 physician investigators, 4 clinical research assistants and 4 clinical research data managers to conduct in vivo clinical trials to assess the efficacy of chloroquine against P. vivax blood stage infections and primaquine for preventing relapse of P. vivax; 2) Train 3 principal investigators and 9 microscopists in the methodologies of the currently available malaria diagnostics (microscopy, rapid diagnostic tests and polymerase chain reaction) and understanding the benefits and pitfalls of each method and the impact of misdiagnosis on treatment outcomes; 3) Train 3 principal investigators and 12 epidemiology research assistants in the epidemiology of vivax malaria in urban and rural areas and 4) Train 2 instructor/evaluators and 40 technicians in microscopic diagnosis of malaria (training modules, quality assurance, testing, and certification), antimalarial integrity testing and Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency testing. Utilizing available expert faculty at the U.S. Naval Medical Research Unit #2 (NAMRU-2) and CNM, these aims will be met by providing didactic modules and practical experience in designing, planning and executing clinical trials and analysis of results; conducting diagnostic tests and evaluating results in the context of individual patient and public health impact; planning and executing cross-sectional and prospective malariometric surveillance activities; malaria microscopy; G6PD testing and antimalarial compound analysis. As this training occurs, critical public health information will be accumulated while preparing a cadre of vivax malaria control experts to conduct these activities independently at close of the program.